Continuous reactions using ionic liquids as catalytic phase

There are many good reasons to study ionic liquids as catalyst phases in continuous processes. Besides the engineering advantage of their non-volatile nature, their adjustable solubility and coordination properties are of special interest as they allow a systematic optimisation of ionic liquid-organic biphasic catalysis, ionic liquid-compressed CO2 biphasic catalysis as well as supported ionic liquid phase (SILP) catalysis. But which catalytic reaction should be optimized using the ionic liquid approach? This contribution summarizes in its first, general part important pre-requisites with respect to reactants, products, catalytic active species and reaction conditions that make continuous catalytic operation using ionic liquids more or less promising. In the second part different examples from published process development studies are presented illustrating the aforementioned principles and demonstrating different options for technical realisation.